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SubjectRe: Would Linux still be Linux if it didn't have an MMU was Re: Linux Port to NS486? (without MMU)
Date
> When I read the man page for mmap it states that
> "Linux 0.99.11 can't map files etc., and can't do
> other things documented here" -- I probably have
> old manpages. This leads me to think that early
> linux didn't have much support for mmap.

Page mapping is used as the basis for the whole VM
and much of the I/O subsystem. Its used for shared
libraries, for system5 shared memory and for mmap.

To build a kernel without it is possible, you'd need
to go back to the old disk I/O system, drop the
shared libraries (initially anyway - its in theory
possible to build the shared libraries specially to
use a different segment - not nice though).

You can keep all the protection and stuff as the segmented
architecture still has permissions. You'd end up with a
Linux kernel that needed the VM stuff rewriting, the
paging changed to swapping, and the old style disk I/O
code using. Doable but not trivial

Alan


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